This research project investigates how the introduction of the performance-based human resource management reforms of Japanese firms affect changes in organizational commitments of Japanese employees to them, which are well-known as the long-term ones. Recently Rousseau (1992) and her colleagues propose the new concept as "psychological contract" to these changes in implicit interpretation about obligations and benefits of employment contracts between employers and employees. Through the HRM reforms, the main targets of Japanese employers appear to shift from the long-term job security which encourages employees to develop the company-specific skills to the job employability which encourages employees to develop short-term competencies. They also appear to change from the long-term commitments to short-term ones. We tried to investigate such changes. In the year 2003, we studied several cases of the typical electronics companies and knew that although they introduce the performance based HRM reforms and focus on the short-term competency-building, they also suffer from employees' growing dissatisfaction from these reforms. In the year 2004, we further did the survey about the performance based HRM reforms and changes of employees' organizational commitments and psychological contracts for three companies in the Western Japan. We got interesting results from this survey about Japanese employees' changing psychological contract. In the younger generation, more employees have the psychological contract with the short-termism that employees mainly commit to their firms for their career development or for earning money, although many of older managers support seniority-based employment system and many of older workers only seek for the long-term job security.